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    Categories Networking TechnologyPerformance Monitoring

A T1 Isn’t What It Used To Be: Why Remote Site Bandwidth Affects Application Performance

This past summer, I wrote about T1s and three best practices for WAN Performance. As I mentioned in that post, T1-class WAN services are a popular way to connect branch offices to corporate data centers and the Internet for voice and other application services.

While the 1.54Mbps definition of a T1 hasn’t changed over time, it’s now common to see multiple T1 services bonded to provide 3 and 6Mbps speeds. The challenge is that even at 6Mbps, WAN speeds are falling behind the demand caused by mobile users, streaming content, BYOD and continued growth of cloud services in the workspace.

The screenshot below is taken from PathView Cloud, monitoring the total capacity, path utilization, latency, loss and jitter over a T1 circuit connecting a retail site to a regional data center. As you can see from a recent day’s results, utilization of the path exceeds the user-defined utilization threshold of 70% several times throughout the day. At the same time as utilization peaks, you see excessive levels of packet loss. This level of degradation can wreak havoc on point-of-sale, data backup and communications services.

If you suspect your network is being over utilized and application performance is suffering as a result, you really need to track bandwidth usage by application and host. Traditional Netflow tools are usually blind to popular web services delivered from content delivery providers like Akamai, so consider bandwidth analysis tools that include continuous deep inspection.

We use our own PathView Cloud solution to monitor bandwidth use at our main office in Boston. On any given day we see traffic from Office365, Salesforce.com, hosted Voice over IP, web browsing load from an active sales team, multiple Citrix Online sessions and more. In the below screenshot, you can see the top 20 applications that are driving bandwidth consumption from a recent work day. YouTube can easily consume 1Mbps or more with a single streaming session.

As we’ve been talking about lately, a legacy WAN circuit bandwidth crunch can easily collide with growing bandwidth demand, and the results include negative end user application experience. Here are some parting recommendations:

  1. Know how much bandwidth you need by application and concurrent session requirements. Make a per-site plan based on office type, number of workers, devices, and WAN options.
  2. Validate that your WAN provider is delivering the actual capacity you’ve contracted. You can use one of our free capacity test tools such as PathTest, or better yet monitoring this continuously with PathView Cloud.
  3. Monitor actual bandwidth use by application and user with a strategy that includes deep inspection of traffic.
  4. If you’re including voice and video conferencing traffic on the same WAN circuit, be sure to employ and test quality of service (QoS) as recommended by our equipment vendor.
Christine Cignoli: Christine Cignoli is a technology writer based in Boston. She's written about storage, data center infrastructure, virtualization and enterprise apps for more than ten years, and has a master's in publishing and writing from Emerson College.